Sibster 

A non-binary sibling. Historically your sister.

“I asked Jordan if I should say ‘sibling’ or ‘sister’ in reference to them. They said they like the term ‘sibster.’”

“My sibster Alex drew this! They are such a good artist.”

Sibster by gnattatat October 9, 2019

sibster 

A sibster is a person who acts like everyone's sister. A sibster has lots of friends and pals, because they are very friendly. A sibster is like a sister but is of no blood relation.

"Nat's my sibster, ya know?"

sibster by verydifferentname July 14, 2006

Sibster 

Gender neutral term to refer to a sibling. Often used as a replacement for sister/brother.

This is my sibster Kai, they are really good at smash Bros.

Sibster by Death_is_inevitable December 2, 2021

sibster 

a sibling who is a sister

I have three wonderful sibsters.

sibster by Qith March 28, 2009

Plump Sister 

A woman who has put on a few pounds since the last time that a random 72 year old Uncle will say to Larry, the cousin twice removed, this kind of thing:

Uncle: "Golly! That's Suzanne? She has gotten to be a real Plump Sister since the last time I saw her."
Larry: "Must've been back in the Seventies. Before the kid. Kids. Who knows."

Uncle: "It was May 1979. When they got married...wow she just blimped out!" Larry: "Total butterball. Plump Sister, shame."

Plump Sister by MissPriss9 January 12, 2019

Sister X 

The sister with the most not-relative-siblings in Vietnam.

- Do you know sister X?
- Of course, she's the one with the most siblings in Vietnam.

Sister X by Bé Iu Của Chị X April 23, 2021

Big Sisters & Big Brothers 

Organizations that pair young kids with older "brothers" & "sisters". They spend quality time together & it makes up for not having a Mom or Dad. Great for youngsters!

{Big Sisters & Big Brothers] are in practically every town & city nationwide.

Big Sisters & Big Brothers by Starchylde May 21, 2016